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Proceedings Paper

Surface plasmon enhanced FRET
Author(s): Jennifer M. Steele; Chae M. Ramnarace; William R. Farner
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Paper Abstract

We demonstrate an increase in Förster Resonance Energy Transfer (FRET) efficiency for paired fluorescent molecules on gold nanogratings for a range of acceptor concentrations. For gratings, the periodicity allows for a broad range of surface plasmon wavelengths that follow a dispersion relationship. The dispersion relationship is determined by the periodicity of the grating and the dielectric function of the metal that makes the grating. Locating a fluorophore near a plasmonic metal structure increases the emission in two ways – an excitation enhancement and an emission modification. The second mechanism occurs when the plasmonic substrate increases the local density of optical states (LDOS). This has the effect of shortening the lifetime of the excited state which increases the quantum yield of the fluorophore. In this work, gold wire nanogratings with a period of 500 nm were fabricated. We used Atto 532 and Atto 633 as the donor and acceptor FRET molecules respectively. A thin layer of PVA containing different concentrations of the donor and acceptor FRET molecules was spun cast onto the gratings. The donor molecules were excited with a 532 nm laser, and the fluorescence emission from both the donor and acceptor molecules were recorded. We found that for all concentrations of acceptors, the FRET efficiency was the largest when the surface plasmon modes overlapped the acceptor emission. Compared to the unenhanced efficiency, the largest gains in efficiency were measured for the lowest concentration of acceptors.

Paper Details

Date Published: 29 August 2017
PDF: 7 pages
Proc. SPIE 10353, Optical Sensing, Imaging, and Photon Counting: Nanostructured Devices and Applications 2017, 103530U (29 August 2017); doi: 10.1117/12.2274218
Show Author Affiliations
Jennifer M. Steele, Trinity Univ. (United States)
Chae M. Ramnarace, Trinity Univ. (United States)
William R. Farner, Trinity Univ. (United States)

Published in SPIE Proceedings Vol. 10353:
Optical Sensing, Imaging, and Photon Counting: Nanostructured Devices and Applications 2017
Manijeh Razeghi; Oleg Mitrofanov; José Luis Pau Vizcaíno; Chee Hing Tan, Editor(s)

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